diff --git a/header-auth.go b/header-auth.go
index 5ead0a62..e030af2a 100644
--- a/header-auth.go
+++ b/header-auth.go
@@ -13,7 +13,7 @@ type HeaderAuth struct {
 	Values map[string]string
 }
 
-var regHeaderAuthKeyValue = regexp.MustCompile("^([a-z]+)=(\"(.+?)\"|([a-zA-Z0-9]+))(, *|$)")
+var regHeaderAuthKeyValue = regexp.MustCompile("^([a-z]+)=(\"(.*?)\"|([a-zA-Z0-9]+))(, *|$)")
 
 // ReadHeaderAuth parses an Authenticate or a WWW-Authenticate header.
 func ReadHeaderAuth(in string) (*HeaderAuth, error) {
diff --git a/header-auth_test.go b/header-auth_test.go
index 483a910b..3b525a57 100644
--- a/header-auth_test.go
+++ b/header-auth_test.go
@@ -63,7 +63,7 @@ var casesHeaderAuth = []struct {
 		},
 	},
 	{
-		"digest response",
+		"digest response 1",
 		`Digest username="aa", realm="bb", nonce="cc", uri="dd", response="ee"`,
 		`Digest realm="bb", nonce="cc", response="ee", uri="dd", username="aa"`,
 		&HeaderAuth{
@@ -77,6 +77,21 @@ var casesHeaderAuth = []struct {
 			},
 		},
 	},
+	{
+		"digest response with empty field",
+		`Digest username="", realm="IPCAM", nonce="5d17cd12b9fa8a85ac5ceef0926ea5a6", uri="rtsp://localhost:8554/mystream", response="c072ae90eb4a27f4cdcb90d62266b2a1"`,
+		`Digest realm="IPCAM", nonce="5d17cd12b9fa8a85ac5ceef0926ea5a6", response="c072ae90eb4a27f4cdcb90d62266b2a1", uri="rtsp://localhost:8554/mystream", username=""`,
+		&HeaderAuth{
+			Prefix: "Digest",
+			Values: map[string]string{
+				"username": "",
+				"realm":    "IPCAM",
+				"nonce":    "5d17cd12b9fa8a85ac5ceef0926ea5a6",
+				"uri":      "rtsp://localhost:8554/mystream",
+				"response": "c072ae90eb4a27f4cdcb90d62266b2a1",
+			},
+		},
+	},
 }
 
 func TestHeaderAuthRead(t *testing.T) {